Different types and kinds of liquid crystal display panel systems for producing either single color or multicolored display images, are known. Such display systems may, for example, be employed with overhead or other projectors for projecting the images onto screens, or may serve as computer screens or the like. A typical liquid crystal display (LCD) panel in such a system, includes liquid crystal material, sandwiched between a pair of overlying protective glass panel substrates. Said panel is normally used with other optimal elements such as polarizer lens or other LCD panels. While such LCD panels have been satisfactory for many applications, there have been problems with their use. For example, media differences between the glass elements enclosing the liquid crystal material and other optical components, can cause a less than satisfactory interface between disparate materials in a typical system. As a result, there can be unwanted and undesirable intra element light reflections, refractions and resulting losses. Thus, a less efficient and effective system can result.
In some applications, such undesirable characteristics and losses are accentuated. For example, stacked panels enable colored images to be produced, but stacking increases the number of system elements, thereby also increasing the likelihood of unwanted reflections, refractions and losses. In addition, in some stacked panels, a diminution of light passing through the panels, with a concomitant diminution of color intensity, occurs. In view of the foregoing, it would be highly desirable to have a liquid crystal panel system having elements which could be optically coupled to minimize or at least reduce greatly, intra element light refractions, reflections and losses, and yet provide improved operating characteristics.
In general, the problems of unwanted optical characteristics and resulting losses often present severe limitations in liquid crystal display systems, because of the critical, precise required optical characteristics such panels must usually possess. In a typical nematic LCD panel, whether the panel is utilized in overhead display systems, in computers, or in other applications, scattered incoming light is passed through a polarizer, and an LCD panel causes an electro-optical rotation of the polarized light by a predetermined twist angle, to cause the rotated light to pass through an output polarizer. Moreover, such electro-optic light rotation occurs for each one of a large number of liquid crystal pixel elements individually as they are scanned during each image frame. Thus, as a result of the precise nature of the light path, through the LCD panel, the optics within the panel must be very carefully aligned over the entire area of the matrix area of pixel elements. Thus, any losses or other optical problems with the construction of a typical LCD panel can be enhanced due to the many different light paths being selectively rotated during each scanning cycle, as each small light path is guided through the various optical elements, such as the polarizers and LCD panels.
Moreover, the use of glass substrates can introduce losses in the system. Thus, diminished transmissivity and intensity of desired components of the light can be experienced.
Thus, it is well recognized that liquid crystal display panel systems, especially those systems which include two or more individual LCD panels stacked along a common optical path, frequently exhibit unwanted intra element light reflections, refractions and losses. Therefore, it would be highly desirable to provide an LCD panel construction having elements which are optically coupled in an improved manner to minimize or at least reduce greatly unwanted light reflections, refractions and losses. Such an LCD panel construction should also possess an improved system transmissivity, without sacrificing desired optical properties such as optical retardation, rotation, or spectral filtering. Such a configuration could also be used to augment any of the above optical properties such as retardation or spectral filtering.